A carbonate ester is a compound useful as a synthetic raw material for aromatic polycarbonates and pharmaceuticals and agricultural chemicals. A known process for producing a carbonate ester is one that carries out synthesis by a gas phase reaction using carbon monoxide and nitrite in the presence of a platinum group metal solid catalyst (see, for example, Patent Literatures 1 and 2). In such a process, a carbonate ester can be obtained by the following reaction formula (i):CO+2RONO→ROC(═O)OR+2NO  (i)
In the production methods of Patent Literatures 1 and 2, an intended compound is produced by a catalytic reaction while recycling alkyl nitrite as a raw material. In such a production method, a target compound can be mass produced by scaling up an apparatus.
Patent Literature 2 proposes a technology for preventing the catalytic activity reduction by detecting a concentration of nitrogen monoxide in a supplied gas and adjusting an amount of the molecular oxygen to be supplied based on the obtained concentration. Patent Literature 3 proposes a technology for removing a by-produced halide (see, e.g., Patent Literature 3).